The invention relates to an apparatus in spinning preparation for feeding a plurality of charging shafts, especially a mixer, with fibre material.
Fibre material may be transported, for example pneumatically, in a supply channel and deflected into the charging shafts by means of deflecting devices, each charging shaft being closable at its upper end by means of a rotary gate which, in its open position, closes off the cross-section of the supply channel. From a given batch of bales it is necessary to produce, in rationalised manner, a mixture in which optimum distribution of the starting material in respect of staple length, fineness, maturity degree, colour etc. is always ensured. The mixture not only forms the basis for producing yarns of consistently high quality in respect of uniformity, tear strength, dye take-up characteristics etc. but also improves the running properties of the material during subsequent processing. A multi-mixer, for example a Universal MX-U mixer, which can be constructed with 6, 8, 10 or 12 chambers, is used for the production of a homogeneous mixture of such a kind. The doubling number (flock doubling) corresponds to the number of chambers. Doubling results especially in the mixture being made more uniform, that is to say doubling is intended to equalise variations in the fibre material.
The hourly production rate and mixing quality are the fundamental performance features of a mixer. A method using a known mixer, the MPM mixer, has a production output of 600 kg/hour in the case of six chambers and of 1200 kg/hour in the case of twelve chambers so that a high hourly production rate is achieved. The quality of the mixture is crucially governed by how evenly flaws present in the supplied material are distributed in the quantity of fibre material. Crucial for the quality of the mixture and, therefore, the main function of the mixer altogether is the distribution of the flaws within as large a fibre quantity as possible, that is to say the equalisation of medium-duration and long-duration flaws in the composition of the supplied fibre material. The greater the quantity of fibre material in which the flaws that are present are to be uniformly distributed, the greater is the success of that equalisation and, therefore, the quality of the mixture. Short-duration flaws, that is to say flaws relating to small fibre material quantities, are already equalised in part on bale opening. Modern bale openers, for example the BLENDOMAT BO-A, already limit, as a result of their flock removal, the magnitude of flaws to very small levels from the outset.
In a known apparatus, a crank mechanism is associated with the rotary gate. The straight-slider crank has identical advance and return times, that is to say an idle time of 50%. A further disadvantage is that the connecting rod is subjected to bending stress. In addition, it is a problem that only a small amount of torque can be transmitted.
It is an aim of the invention to provide an apparatus of the kind mentioned at the beginning that avoids or mitigates the mentioned disadvantages and that especially increases the efficiency by means that are simple in terms of construction and, above all, improves transmission of the drive movement to the movement of the rotary gate.